Loss Separation in Hard- and Soft-Switching GaN HEMTs operated in a 10 kW Isolated DC/DC Converter

In this paper, GaN power transistors are operated in a 10 kW isolated DC/DC converter, investigating their loss distribution. Based on a combination of calorimetric loss-, and clamped drain source voltage measurements, the losses are separated in conduction and switching losses. Furthermore, the influence of dynamic $R_{\mathrm{on}}$ effects is identified during continuous operation. The chosen ZCZVS topology allows for comparison of hard- and soft-switching operation of the GaN devices. The loss separation reveals almost twice of additional dynamic $R_{\mathrm{on}}$ losses in the hard switching leg. In this case, the dynamic losses account for about one third of the conduction losses.